This invention relates in general to a pump trap assembly for liquid pumping systems, and in particular, to a pump trap assembly having multiple pivot axes for decreasing the travel distance needed for the float arm to actuate the valve mechanism.
Pump trap assemblies with valve actuating mechanisms are useful in controlling the filling of a closed or sealed pressure vessel. For example, in U.S. Pat. No. Re 34,957 to Francart, Jr., the pressure vessel includes a vent valve for venting the interior of the vessel to the surrounding atmosphere and a second pressure valve subjected to high pressure inlet fluid. During filling of the pressure vessel, the vent valve is in the open position and the pressure valve is closed by a single-float operated over-center valve actuating mechanism. As the vessel fills with fluid, the float rises and a rotatable float arm, forming part of the valve actuating mechanism, is swung or rotated about a pivot point at one end, causing an over-center toggle linkage mechanism to move toward the center position against a spring bias. Such a mechanism has toggle linkage elements which snap quickly through the center position, closing the vent valve while simultaneously snap opening the high pressure inlet valve to pump the accumulated liquid from the vessel. Typically a tension or compression coil spring provides such a biasing force with one end of the coil spring coupled to a fixed or stationary member of the valve mechanism or vessel. In other cases, such tension coil spring is coupled at opposite ends to moveable elements of the valve actuating mechanism.
While such over-center snap-acting valve mechanism for steam condensate pumps and fuel feeding systems operate satisfactory to automatically control the liquid feed to and discharge from the pressure vessel, such known mechanisms are complex and expensive. Further, conventional pump trap assemblies are designed such that the float ramn and the linkage mechanism pivot about the same axis. As a result, the pump trap assembly requires that the float arm move a relatively large amount of travel distance to cause the linkage mechanism to snap through the center position, thereby increasing the overall size of the pump trap assembly.
It is, therefore, an object of the invention to provide a pump trap assembly that decreases the travel distance necessary for the float arm to cause the linkage mechanism to snap through the center position to close the vent valve and open the inlet valve.
It is another object of the invention to provide a pump trap assembly that can be positioned in locations that require a relatively small amount of clearance as compared to a conventional pump trap assembly.
It is yet another object of the invention to provide a pump trap assembly that includes a plurality of pivot axes for decreasing the travel distance necessary for the float arm to cause the linkage mechanism to snap through the center position.
It is still another object of the invention to provide a pump trap assembly that does not require adjustments of the float arm and spring arms.